The invention relates to an adjustable rigid tire building drum used for manufacture of rubber tires of many different sizes.
The tire building drums used for supporting off-the-road (OTR) tires during tread strip winding operations must have high strength and rigidity to provide proper support and must also be collapsible to clear the beads during removal of the tire. It is standard practice to employ a large number of such drums in various lengths and diameters for use in building OTR tires of different sizes. These drums are large and heavy and occupy an enormous amount of space in a tire manufacturing plant. Their size and weight also make it difficult to replace drums on the tread strip winding machine when preparing to make tires of a different size.
Normally the carcasses of the OTR tires have beads with an internal diameter at least 25 percent less than the diameter of the major portion of the carcass being supported by the drum, and this presents a serious problem when removing the tire from a conventional collapsible drum. It often becomes necessary to remove or omit one of the segments of the conventional drum in order to permit such removal. Also the tire is frequently damaged by contact with portions of the collapsed drum as it is removed axially from the drum assembly.
The limitations of the conventional equipment in tire manufacturing plants place undesirable restrictions on the shape of the green OTR tire and limit the radial depth from the bead to the cylindrical external surface of the carcass because of the problems referred to above. The use of conventional collapsible drums have also resulted in tires of inferior quality when segments of the drum have had to be removed.